The present invention relates to a laser scanner for projecting pulsed laser beams to scan over total circumference, for measuring a multiple number of points at high speed and for acquiring three-dimensional position data at the multiple number of points.
In the past, a line scanner has been known as a laser scanner, which projects a single pulsed laser beam on a straight line for scanning and acquires distance measurement data for each pulse.
In recent years, there have been increasing demands to acquire data at higher speed over total circumferential direction of 360°. In case it is necessary to acquire the data over total circumferential direction, a plurality of line scanners are used to acquire the data. In this case, a plurality of costly line scanners are needed, and much time and more working operations have been needed for the adjustment of the acquired data.
As a device for acquiring data at a multiple number of points in total circumferential direction at higher speed, a laser scanner is known, which is used to acquire the data by projecting a plurality of beams (multi-beams) for scanning at the same time. Such type of laser scanner is disclosed, for instance, in the International Patent Publication 2008-008970. The International Patent Publication 2008-008970 discloses a laser scanner, which projects the plurality of laser beams in straight-line arrangement (e.g. in vertical arrangement) and scans in a direction perpendicularly crossing the arraying of laser beams (e.g. in horizontal direction). As a result, multi-point data in planar arraying are acquired.
In the laser scanner as described above, all components of the measuring system are disposed on a rotating unit, and the laser scanner has a structure where a rotating unit with high weight is rotated at high speed. As a result, the structure must be strong and solid and must have high accuracy. Accordingly, the laser scanner is costly.